Coalescence of thermal fractures initiated at parallel cooling surfaces
ISSN: 0264-4401
Article publication date: 12 October 2023
Issue publication date: 5 December 2023
Abstract
Purpose
Thermal fractures initiated under cooling at the surfaces of a 2-D or 3-D structure propagate, arrest and coalesce, leading to its structural failure and material-property changes, while the same processes can happen in the rock mass between parallel hydraulic fractures filled with cold fluid, leading to enhanced fracture connectivity and permeability.
Design/methodology/approach
This study used a 2-D plane strain fracture model for mixed-mode thermal fractures from two parallel cooling surfaces. Fracture propagation was governed by the theory of linear elastic fracture mechanics, while the displacement and temperature fields were discretized using the adaptive finite element method. This model was validated using two numerical benchmarks with strong fracture curvature and then used to simulate the propagation and coalescence of thermal fractures in a long rock mass.
Findings
Modeling results show two regimes: (1) thermal fractures from a cooling surface propagate and arrest by following the theoretical solutions of half-plane fractures before the unfractured portion decreases to 20% rock-mass width and (2) some pairs of fractures from the opposite cooling surfaces tend to eventually coalesce. The fracture coalescence time is in a power law with rock-mass width.
Originality/value
These findings are relevant to both subsurface engineering and material engineering: structure failure is a key concern in the latter, while fracture coalescence can enhance the connectivity of thermal and hydraulic fractures and thus reservoir permeability in the former.
Keywords
Acknowledgements
This work was supported by the Assistant Secretary for Fossil Energy, National Energy Technology Laboratory, U.S. Department of Energy, under award DE-AC02-05CH11231 with Lawrence Berkeley National Laboratory (LBNL) for the project of National Risk Assessment Partnership (NRAP), National Natural Science Foundation of China (U2240210, 52209129) and Hohai University International Cooperation and Exchange Seed Funding Program.
Citation
Chen, B., Zhou, Q. and Wang, Y. (2023), "Coalescence of thermal fractures initiated at parallel cooling surfaces", Engineering Computations, Vol. 40 No. 9/10, pp. 2288-2302. https://doi.org/10.1108/EC-10-2022-0634
Publisher
:Emerald Publishing Limited
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